Author's response to reviews Title: Factors influencing the surgery intentions and choices of women with early breast cancer: the predictive utility of an extended Theory of Planned Behaviour Authors:

Background: Women diagnosed with early breast cancer (stage I or II) can be offered the choice between mastectomy or breast conservation surgery with radiotherapy due to equivalence in survival rates. A wide variation in the surgical management of breast cancer and a lack of theoretically guided research on this issue highlight the need for further research into the factors influencing women’s choices. An extended Theory of Planned Behaviour (TPB) could provide a basis to understand and predict women’s surgery choices. The aims of this study were to understand and predict the surgery intentions and choices of women newly diagnosed with early breast cancer, examining the predictive utility of an extended TPB. Methods: Sixty-two women recruited from three UK breast clinics participated in the study; 48 women, newly diagnosed with early breast cancer, completed online questionnaires both before their surgery and after accessing an online decision support intervention (BresDex). Questionnaires assessed views about breast cancer and the available treatment options using items designed to measure constructs of an extended TPB (i.e., attitudes, subjective norms, perceived behavioural control, and anticipated regret), and women’s intentions to choose mastectomy or BCS. Objective data were collected on women’s choice of surgery via the clinical breast teams. Multiple and logistic regression analyses examined predictors of surgery intentions and subsequent choice of surgery. Results: The extended TPB accounted for 69.9% of the variance in intentions (p <.001); attitudes and subjective norms were significant predictors. Including additional variables revealed anticipated regret to be a more important predictor than subjective norms. Surgery intentions significantly predicted surgery choices (p <.01). Conclusions: These findings demonstrate the utility of an extended TPB in predicting and understanding women’s surgery intentions and choices for early breast cancer.